Health Library

Has your doctor suggested you get screened for colon or rectal cancer? Maybe you have a family history of the disease. Or perhaps you’ve reached an age that makes this screening a smart move. Experts say if everyone ages 50 and older had regular colorectal cancer screenings, at least 60 percent of deaths from these cancers could be avoided.

Know your options

The majority of colorectal cancers begin with a polyp—a growth in the colon or rectal lining. Many screening tests are aimed at finding these polyps so they can be removed before they become cancerous. Less commonly, cancer may develop from flat, slightly depressed areas of colon tissue, called nonpolypoid lesions. Some screening tests detect these lesions, too. Discuss with your healthcare provider which screenings are best for you:

Colonoscopy. This test uses a thin, lighted instrument to view the inside of the entire colon and rectum. If any precancerous polyps, growths, lesions or suspicious tissues are found your doctor may also remove them or take a biopsy at the same time. This test requires preparation to thoroughly clean the colon and is typically performed under sedation. Uncommonly, bleeding, tearing or perforation of the colon lining may occur.

Virtual colonoscopy. This test uses computerized tomography (special X-rays) to assemble pictures of the colon and rectum into detailed images that can show abnormalities. Preparation to cleanse the colon is required; but the test is less invasive than a standard colonoscopy and doesn’t require sedation. But if the test finds something suspicious, you’ll need a traditional colonoscopy to confirm the finding and get a biopsy.

Sigmoidoscopy. Using a lighted instrument, doctors view the rectum and lower colon lining. Polyps and other suspicious tissues may be removed or biopsied; however, growths in the upper colon would not be detected. Preparation to thoroughly clean the colon is required.

Double contrast barium enema. After giving you an enema of a barium solution, doctors introduce air into the colon. Both the barium and the air provide contrast to help outline the colon and rectum and a series of X-rays are taken.

Fecal occult blood tests (FOBT). These tests analyze a small stool sample to detect trace amounts of blood. Finding blood in the stool may indicate the presence of polyps or cancer.

Scientists continue to study these tests to determine how well they detect early-stage disease and save lives and their potential risks.